The number of reports within the literature describing plant response to Al3+ exposure reflects a widespread and growing concern about the effects of Al3+ release. Release of this potentially toxic element can occur through several processes, including profound environmental disturbance such as coal mining or "acid rain". We propose to test the hypothesis that the a symbioticfungus Pisolithus tinctorius growing on pine roots will increase tolerance of seedlings to Al3+, and thus will increase plant survival following toxin exposure. New techniques including magnetic resonance imaging (MRI as is used for medical diagnostics) and NMR spectroscopy of intact plants will be used to assess the effect of the fungus and toxin exposure on root growth, turnover and architecture and chemistry. Ultrastructural changes and localization of Al and P will also be determined. Seedlings inoculated with P. tinctorius and planted on two mine sites will also be studied, with the goal of confirming a beneficial effect of the symbiotic fungus in promoting ecosystem restoration. Specific contributions include: 1) dynamic views of root growth, architecture and turnover as a function of Al3+ exposure and mycorrhizal colonization, 2) determination of Al chemistry within intact roots, 3) determination of the effects of Al3+ on P metabolism 4) ultrastructural information and elemental localization, 5) correlative information from field trees, 6) confirmation of the role of P. tinctorius in providing protection to the host against Al3+ toxicity, and 7) further development of 27Al NMR spectroscopic technology which can be extended to additional studies.